Earthworms activity

Research assistants with the Darwin Correspondence Project joined the teaching team for a new Freshman Seminar at Harvard College called “Getting to Know Darwin.” The class was composed of first year undergraduates and was taught by Ned Friedman, Director of the Arnold Arboretum at Harvard University and Professor in the Department of Organismic and Evolutionary Biology. Here is a link to a feature about the course.

To learn about Darwin’s work on worms, the class collaborated with students at the New England Conservatory (NEC) to replicate some of Darwin’s experiments. The NEC students brought a bassoon, a piccolo, and a piano and our class brought two pots full of earthworms. Using these materials, we were able to imitate the experiments Darwin used to understand the hearing power of worms. In Chapter 1 of Vegetable Mould and Earth-worms, Darwin explained:

Worms do not possess any sense of hearing. They took not the least notice of the shrill notes from a metal whistle, which was repeatedly sounded near them; nor did they of the deepest and loudest tones of a bassoon. They were indifferent to shouts, if care was taken that the breath did not strike them. When placed on a table close to the keys of a piano, which was played as loudly as possible, they remained perfectly quiet.[1]

In spite of the NEC student’s best efforts to incite movement in the worms by playing their instruments, the worms remained unaffected, just as Darwin had observed.

After satisfactorily illustrating that the worms did not notably react to any of the sounds Darwin mentioned, the students sought to observe the effect of vibrations upon worms. In Vegetable Mould and Earth-worms Darwin wrote:

Although they are indifferent to undulations in the air audible by us, they are extremely sensitive to vibrations in any solid object. When the pots containing two worms which had remained quite indifferent to the sound of the piano, were placed on this instrument, and the note C in the bass clef was struck, both instantly retreated into their burrows.[2]

To replicate this portion of Darwin’s work, the students placed two thin plastic pots full of earthworms atop a piano. The NEC pianist then played all of the musical notes Darwin mentioned (along with a few pieces of music). A few of the worms in our experiment retreated slowly into the dirt, but our results were not quite as dramatic as those reported by Darwin. In spite of our lack of definitive results, this experiment provided a great opportunity to engage firsthand with Darwin’s work. Even better, this experiment can be easily recreated almost anywhere: all you need are some worms and some instruments. Try it now and see if your worms are reactive to sound and/or vibrations!

We are currently working on a video of this experiment. Please check back soon to see it!